In general, a hydraulic excavator as a typical example of a revolving type construction machine is largely constituted by an automotive lower traveling structure, an upper revolving structure that is rotatably mounted on the lower traveling structure through a swing circle, and a working mechanism provided on the front portion side of the upper revolving structure. A revolving apparatus is provided between the lower traveling structure and the upper revolving structure, and the upper revolving structure is configured to be revolved on the lower traveling structure by operating this revolving apparatus.
The revolving apparatus includes a reduction device which is mounted on the upper revolving structure and reduces a speed of input rotation and outputs a reduced rotation, a revolving motor such as an electric motor which is provided on the upper side of the reduction device and inputs rotation of a motor shaft to the reduction device, an output shaft which outputs the rotation of the motor shaft whose speed was reduced by the reduction device to the swing circle, and a wet brake device which applies a braking force to the rotation of the revolving motor.
The wet braking brake of the revolving apparatus largely constituted by a brake case in which the rotational shaft is rotatably fitted, a rotating side brake disk arranged outside in the radial direction from the rotational shaft in the brake case, a non-rotating side brake disk arranged in the brake case in a state overlapping with the rotating side brake disk, a brake piston which applies a braking force to the rotational shaft by pressing the rotating side brake disk and the non-rotating side brake disk so as to frictionally engage them with each other, a lubricant oil inlet port provided in the brake case and into which lubricant oil flows, and a lubricant oil outlet port provided in the brake case and from which the lubricant oil therein flows out (Patent Document 1).